If we wanted to match a character a bit more specifically than ., we could use [ and ] (square brackets) to specify a subset of characters that should be matched:

$ grep dev.hda[12] /etc/fstab
/dev/hda1       /boot           reiserfs        noauto,noatime,notail 1 2
/dev/hda2       swap            swap            sw 0 0

As you can see, this particular syntactical feature works identically to the [] in "glob" filename expansions. Again, this is one of the tricky things about learning regular expressions -- the syntax is similar but not identical to "glob" filename expansion syntax, which often makes regexes a bit confusing to learn.